I have noticed the same behavior. It would actually work for one item. But not multiple:
> base: option = b1 b2 b3 b4 > extension: option -= b2
would result in: b1 b3 b4
I have noticed the same behavior. It would actually work for one item. But not multiple:
> base: option = b1 b2 b3 b4
> extension: option -= b2
would result in: b1 b3 b4